The introduction of unwanted sounds is a common problem encountered in audio recordings. These unwanted sounds may occur acoustically at the time of the recording, or be introduced by subsequent signal corruption. Examples of acoustic unwanted sounds include the drone of an air conditioning unit, the sound of an object striking or being struck, coughs, and traffic noise. Examples of subsequent signal corruption include electronically induced lighting buzz, clicks caused by lost or corrupt samples in digital recordings, tape hiss, and the clicks and crackle endemic to recordings on disc.
Current audio restoration techniques include methods for the attenuation or removal of continuous sounds such as tape hiss and lighting buzz, and methods for the attenuation or removal of short duration impulsive disturbances such as record clicks and digital clicks. A detailed exposition of hiss reduction and click removal techniques can be found in the book ‘Digital Audio Restoration’ by Simon J. Godsill and Peter J. W. Rayner, which in its entirety is incorporated herein by reference.